Failure and energy dissipation patterns of tuff under impact loads

This study investigates the failure and energy dissipation patterns of tuff under impact loads with varying occurrence conditions in Dahongshan Copper Mine through Split Hopkinson pressure bar (SHPB) tests, digital image correlation (DIC), fractal dimension analysis, scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Results show that: ① At identical strain rate, the dynamic compressive strength of the 300-level tuff was only 71 % ~77 % of that from the 420-level tuff. ② Both types of specimens underwent a transition from uniform strain, local concentration to crack fragmentation. The 300-level tuff exhibited denser cracks, faster propagation, higher peak strain and higher degree of fragmentation under equivalent impact load. ③ While the crushing energy dissipation density of both types of specimens increased linearly with impact load, the 300-level tuff exhibited significantly higher average energy absorption efficiency (35.86 %) than the 420-level tuff (19.29 %). This study reveals how varying rock microstructures and composition affect the dynamic mechanical properties of ore and rock under impact load, providing theoretical implications for their stability analysis under dynamic load and safe mining.